The invention relates to an electronic module having an electronic component which is arranged within an electromagnetic shielding.
Electronic modules of the abovementioned type are available in a wide variety of electronic devices, for example in vehicle navigation apparatuses or mobile phones. In order to provide sufficient electromagnetic compatibility, such components often have to be shielded in a largely airtight fashion by the electromagnetic shielding, which often leads to problems owing to the necessary conduction away of heat, in particular if the shielding encloses the component relatively closely.
Usually, cooling baffles which pick up heat from the component and emit it into the surroundings via a thermal exchange surface which is as large as possible are used to conduct away heat in electronic components. However in components with a large power loss this leads to an undesirably large power loss on the necessary space.
The invention is based on the object of embodying an electronic module of the type mentioned at the beginning with an electromagnetic shielding in such a way that it can be embodied in as compact a way as possible without problems arising with the conduction away of the heat generated by the component.
This problem is solved according to the invention by virtue of the fact that the electronic component is connected in a thermally conductive fashion to the shielding by means of a thermally conductive element which rests on it.
This configuration according to the invention uses the shielding as a thermal exchange surface for the emission of the heat generated by the electronic component to the air surrounding the shielding on the outside. For this reason, the invention makes it possible to dispense with large-volume cooling baffles. Instead, it is sufficient to use a thermally conductive element which conducts the heat generated in the component into the shielding to a sufficient degree.
If the shielding is formed from the shield frame which extends on each side of a printed circuit board and two shield covers which each close off the shield frame on one side, a particularly simple design of the module is obtained when the thermally conductive element is connected in a thermally conductive fashion to the shield frame.
A particularly effective embodiment is obtained if the thermally conductive element is a bent piece of sheet metal which is attached by one limb to the shield frame and rests with its other limb on the component. Such a thermally conductive element can consist, without regard to the material of the shield frame, of a material which is a good conductor of heat, and have such a thickness that the heat can be conducted away sufficiently quickly and its capacity is sufficient to be able to take up short-term thermal peaks.
The thermally conductive element is mounted particularly easily if, according to another development of the invention, the shield frame has an opening in the vicinity of the thermally conductive element, and the thermally conductive element engages behind the opening with a downwardly directed projection of its limb which bears against the shield frame. This embodiment permits premounting of the thermally conductive elements by virtue of the fact that they are simply inserted into the respective opening and only later fixedly connected to the shield frame by means of screws.
The module can be manufactured particularly cost-effectively if the thermally conductive element is a sheet-metal region of the shield frame which is bent out of the plane of the shield frame and rests on the component from above.
Because the thermally conductive element must be composed of a thermally conductive material, usually aluminum or copper, it cannot press onto the electronic component with sufficient prestressing force owing to its elasticity. A high contact force which is sufficient for a good thermal junction is obtained if the thermally conductive element is held on the component by means of a contact spring which is of bridge-like design and which is supported with one region of its base on the thermally conductive element and has, on each side of the component, a spring leg which is anchored to the printed circuit board.
The contact spring is configured particularly simply if, according to another development of the invention, the two spring legs each lead through an opening in the printed circuit board and are locked to the printed circuit board on the side of the printed circuit board facing away from the component by means of, in each case, one locking projection on the spring leg.